| In this thesis, in order to enhance TbFe magnetostrictive film low magnetic field sensitivity, based on the theory of the exchange-coupling between the magnetostrictive TbFe2 phase and the soft magnetic Fe phase , the microstructures and magnetic performances of TbFe2/α-Fe nano-crystalline exchange-coupling magnetostrictive films and TbFe2/Fe nano exchange-coupling magnetostrictive multiplayers prepared by DC magnetron sputtering were investigated systematically. The results suggest that there exist TbFe2 Laves nano-crystalline phase and α-Fe nano-crystalline phase when annealing temperature is higher than 400℃. With the annealing temperature and the time increasing, the grain sizes of the TbFe2 Laves phase and α-Fe phase increase, but the maximum is less than 30nm. The annealing could reduce the plane coercivity and the saturation magnetization of TbFe films, hence improve the plane soft magnetic performances and low magnetic field magnetostriction. The magnetostrictive coefficient of the TbFe films annealed for 60 mins at 550℃can reach to maximum of 186 ppm at 200 Oe, so the maximum sensitivity can reach to 0.93ppm/Oe. The results of film magnetic domains explored by MFM indicate that for the as-deposited TbFe films, maze domain structures exist, hence it possesses strongly perpendicular anisotropy. After being annealed below 350℃, no clear domain structures are observed, which suggest that the easy direction of magnetization of the TbFe is shifted from perpendicular to in-plane. With the annealing temperatures increase, maze domain structures appear again which imply perpendicular anisotropy increase again. Compared to TbFe magnetostrictive monolayers, fabrication TbFe2/Fe exchange-coupling magnetostrictive multiplayers can improve the plane soft magnetic properties, and then improve the properties of film low magnetic field magnetostriction. The [TbFe2(4.5nm)/Fe(6.5nm)]60 multilayers exhibits the maximum magnetostriction of about 350ppm at 400Oe, so its maximum sensitivity is... |
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